1. Field of the Invention
The present invention relates to a method of controlling a drying cycle in a washing machine.
2. Discussion of the Related Art
Generally, a drum type washing machine adopts a washing system using a friction between a laundry and a drum rotated by receiving a drive force of a motor unit while a detergent water, and laundry are held within the drum. The drum type washing machine is advantageous in causing less damage to the laundry, preventing the laundry from being raveled, and providing washing effects of beating and rubbing.
Meanwhile, in order to cope with the functional improvement and high-quality rend of the rum type washing machine, a laundry-drying function is provided to the drum type washing machine as well as the conventional washing and dewatering functions. Accordingly, the demand for a drum type washier/dryer tends to rise.
The drum type washer/dryer dries a laundry within a drum in a manner of sucking to heat an external air using a fan and heater provided outside a tub and blowing the heated air into the tub.
FIG. 1 and FIG. 2 are cross-sectional diagrams of a drum type washing machine equipped with a drying function according to a related art.
Referring to FIG. 1 and FIG. 2, a cylindrical tub 2 is provided within a cabinet 1 and a cylindrical drum 3 is provided within the tub 2. A drive shaft 4 is installed at a rear side of the drum 3 to be connected to a motor 5. A drive power of the motor is transferred to the drum 3 to rotate. And, a multitude of perforated holes (not shown in the drawings) are formed on an outer circumference of the drum 3 so that air or water can pass through the perforated holes.
In order to perform a drying cycle of the drum type washing machine, t circulation duct 6 is connected to the tub 2 to form a circulation path of heated air. A blower fan 7 for forcibly blowing air to circulate and a heater 8 for heating the blown air are installed within the circulation duct 6.
A cooling water inlet pipe 9 for supplying cooling water from outside for the condensation of air flowing in the circulation duct 6 is connected to an upper part of the circulation duct 6. A tub temperature sensor ‘B’ sensing a temperature within the tub 2 is installed within the tub 2, and a duct temperature sensor ‘A’ sensing a temperature of a circulating air is installed inside the circulation duct 6.
A method of controlling a drying cycle in the drum type washing machine equipped with the drying function according to a related art is explained as follows.
Once a drying cycle is initiated after completion of dewatering, the blower fan 7 is driven to suck air into the circulation duct 6. The air blown to flow in the circulation duct 6 is passed through the heater 8 to be heated at a high temperature and then flows in the drum 3 to exchange heat with a laundry within the drum 3 for drying the laundry.
Meanwhile, the humid air resulting from the heat exchange with the laundry within the tub 2 flows in the circulation duct 6 again by the operation of the blower fan 7. If the hot and humid air is supplied to the heater 8 via the blower fan 7, performance of the blower fan 7 is reduced and efficiency of the heater 8 is considerably lowered. Hence, the cooling water is supplied via the cooling water inlet pipe 9 to condense the hot and humid air flowing from the tub 2. Thus, humidity of the corresponding air is lowered.
As mentioned in the foregoing description, the humidity-lowered air is passed through the heater 8 to be heated at a high temperature and then flows in the tub 2 again, whereby a circulation process of drying the laundry is repeated.
In case of circulating the hot air at the high temperature into the tub 2 in the drying cycle, the motor 5 rotates the drum 3 at a low rotational speed of about 50 RPM so that the hot air can evenly come into contact with the laundry.
In the drum type washing machine equipped with the drying function according to the related art, if a difference (Td−Tt) between a temperature Td sensed by the duct temperature sensor ‘A’ and a temperature Tt sensed by the tub temperature sensor ‘B’ is equal to or greater than a first setup value in each drying cycle mode, if the temperature Td sensed by the duct temperature sensor ‘A’ or the temperature Tt sensed by the tub temperature sensor ‘B’ is equal to or greater than a second setup value, or if a predetermined time expires from the initiation of the drying cycle, the heater 8 stops being driven but the blower fan 7 is operated during a period of time to perform a cool air drying. Alternatively, the drying cycle is further performed during an additional period of time and is then terminated.
However, the related art drum type washing machine equipped with the drying function intends to make the laundry come into contact with the hot air in a manner of rotating the drum 3 at a low rotational speed by driving the motor 5 during the drying cycle. In case of an excessive amount of the laundry, the laundry fails to be evenly distributed to elongate a corresponding drying time. Moreover, the laundry fails to be evenly dried to reduce a drying effect thereof.